Enhanced nutrients removal from low C/N ratio rural sewage by embedding heterotrophic nitrifying bacteria and activated alumina in a tidal flow constructed wetland.

Abstract

Rural sewage treatment facilitates nitrogen and phosphorus removal yet can be costly. To address this challenge, a cost-effective embedding material mainly consisting of heterotrophic nitrifying bacteria, activated alumina (AA), and a solid carbon source (HPMC) was applied to a tidal flow constructed wetlands (TFCWs); aimed at stable nitrogen and phosphorus removal under low carbon-to-nitrogen (C/N) ratios. The TFCWs could be shortened to 16 d of startup duration time compared with the control group; and improved the ammonia nitrogen (NH₄⁺-N), total nitrogen (TN), and total phosphorus (TP) removal efficiencies to 98 %, 93 %, and 68 %, respectively. Also, effluent NH₄⁺-N, TN, and TP in the enhanced TFCWs could be stable at 0.52 ± 0.18, 1.23 ± 0.45, and 0.75 ± 0.25 mg/L, respectively. Microbial community analysis revealed that AA and HPMC were enriched Pseudomonas sp., which potentially accelerated the NH₄⁺-N assimilation pathway and phosphate biological removal. Embedding materials-TFCWs can provide new solutions for integrated rural sewage technology.